Display system for moving subway trains

ABSTRACT

A display system for moving subway trains in which a plurality of consecutive images are mounted on the wall of the subway tunnel and each image is provided with an electronic flash tube and a photoelectric cell. The illumination from the window of the passing train subsequently energizes each photoelectric cell which in turn energizes the flash tube so as to provide a sequence of animated images for a passenger located by the said window.

United States Patent Sollogoub et al. Nov. 28, 1972 [54] DISPLAY SYSTEM FOR MOVING FOREIGN PATENTS OR APPLICATIONS SUBWAY IRAINS 596,613 8/1915 France ..40/125 L [72] Inventors: Nicolas Sollogoub, Outremont,

Quebec; Jean A. Bloc, Montreal, OTHER PUBLICAFI'IONS Quebec, both of Canada General Electric, SCR Manual, th Edition, 1967 [73] Assignee: Agence Katimavik Inc., Montreal, Syracuse New York (pgs' 299) i Canada Primary Examiner-Robert w. Michell [22] Filed: Oct. 3, 1968 Assistant Examiner-Richard Carter Attorney-Raymond A. Robic 211 Appl. No.: 764,778

. ABSIRACT Cl 1 0 1 A display system for moving subway trains in which a [51] Int. Cl. .;..G03b 25/00 plurality of consecutive images are mounted on the [58] Field of Search ..40/ 125 L, 130 L; 307/311; wall of the subway tunnel and each image is provided 250/206, 214; 352/100 with an electronic flash tube and a photoelectric cell. a The illumination from the window of the passing train [56] References Cited subsequently energizes each photoelectric cell which in turn energizes the flash tube so as to provide a UNITED STATES PATENTS sequence of animated images for a passenger located 2,026,753 l/1936 Rosenthal et al. .40/125 L UX by the sand i' 2,299,731 10/1942 Arendt ..40/125 L UX 1 Claim, 4 Drawing Figures ay/flay 22c 20c 226 2015 22a 20a vllllllllll' mlirlllllmllllllllIIIIIIIIIIIIHIIIIIIIIIIIII PAIENTEDwvz I 12 3. 704.064

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I II'IIIIII INVENTORS I Nicolas SOLLOGOUB .leon Antoin. BLOC ATTORNEY 1 DISPLAY SYSTEM FOR MOVING SUBWAY T 1 TRAINS BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention isdirec'ted to the production of animated images displayed on the walls of a subway tunnel for the'benefit'of the passengers in the moving train.

' 2. Description of thePrior Art Display systems for moving vehicles are known wherein the circuit for the illumination of the images is switched on and'off bya physical contact from a part of the train. Other previous arrangements have been contemplated for various circuit systems in order to obtain continuous display effect despite variations in the speed of the vehicle. I

SUMMARYOF THE INVENTION It is an object of the present invention to produce in a subway tunnel, animated pictures for a passenger'of'a subway train, wherein no mechanical contact is required between fixed elements in the tunnel and the moving train for switching the illumination of the image.

The display system according to the invention requires theoretically no modifications to the train itself and a permanently fixed installation in the subway tunnel. Such an arrangement is very economical and commercially practical.

j The small number and the simplicity of the elements involved in the combination render the system reliable and guarantee the synchronization of the flashing with the movement of the train.

The display system for passengers travelling in a subway train may be used for one image only but it is preferably adapted for viewing a plurality of animated images. Each image is mounted with its associated electronic flash tube and photoelectric cell in a way such that the illumination inside the train excites the photoelectric cell through a window of the train and permits the synchronized flashing of the image with the passage of the window before the said image. This process is repeated for each consecutive image.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS. 1 and 2, the subway train '10 moves in the tunnel 12. The wall 14 adjacent the train is used to support a plurality of images 16a, 16b, 16c

. 16g displaying a series of illustrations representing preferably separate steps of a continuous movement. The continuity of the movement moves progressively with images 16a, 16b, 16c, etc. in the direction of movement of the subway train illustrated by the arrow A.

Above each of the images is mounted an electronic flash tube 20a, 20b, 20c, etc. which is located to provide an adequate illumination for viewing the respectiveimages. A plurality of photoelectric cells 22a, 22b, 22 are also-mounted at the upper left corner of .each image for-pickingup the light coming from the window 18'of the train. These cells are located so as to trigger theelectronic flashtubes at the time when -the image is'facing the window 18 of the train 10. As illustrated in FIG. 2, the flash 20a illuminates the image 16a when the window 18 is substantially in front of this image. It may be realized that each photoelectric cell may be located more or less to the left of the image depending on the relativesize of saidimage compared-to the width of the window 18. This varies with the desired synchronization. The photoelectric cells are oriented to pick up the illumination inside the train and consequently as soon as: the left end portion of the window 18 passes in front of the cell, the respective electronic flash tube will be triggered.

,- In order to explain more adequately thecombination of one image with its respective electronic flash tube and photoelectric cell, reference will now be made to FIG. 3. A piece of solid board 24 is fixed to the wall 14 by means of bolts 26 and anchoring nuts 28. The image '16 is fixed upon the surface of the board 28 and substantially levelled withthe window 18. At the upper part of the board, a bracket 30 is fixed so as to support the flash tube 20 extendingaway and above the image 16 for producing an adequate illumination of the image 16 so that a passenger sitting at the window 18 may see it clearly and easily.

The photoelectric cell 22 is mounted into a tubular member which extends in front of the photoelectric cell so as to limit the cone .of light which may reach the cell. The light coming from the window 18 in the direction of the arrow B and within a fairly specific angle is picked up by the cell 22. It has been found that the illumination of the walls of the train opposite the window 18 may-provide sufficient illumination to excite the cell 22 especially if the opposed wall contains a row of fluorescent lights or the like for advertizing purposes. A cone of light=of approximately 20 to 25 degrees has been found suitable in order to eliminate parasitic lights coming from other sources than the window 18. This cone of light-may even be smaller depending on the threshold of the-cell and the intensity of the light from the window 18. The proximity of the window 18 to the photoelectric cell increases the-light received but minimum distances mustbe maintained between the fixed installation on the subway wall and the moving train so as not to interfere with the movement of the said train. The tubular member 32 illustrated in FIG. 3 is pointing upwardlytowards the window 18 so as to be oriented towards-the light having the maximum intensity in the train. As stated above, advertizing panels usually provide this typeof illumination. The electronic flash tube model FT 151 sold by Canadian General Electric and located at approximately 2 feet from the center of the image has been found to provide an adequate illumination. Obviously, the reflectivity of the image itself may change the required intensity of light. A sheet of clear plastic may be used to cover the image so as to prevent soiling of the latter or to facilitate the washing of the same.

Each image is provided with its own time delay circuit in the box 34 which is supplied by a direct current power supply or a rectified alternative current.

The photoelectric cell 22 illustrated in FIG. 3 is represented in FIG. 4 by the resistor R whose resistance varies with the light falling upon it. The flash tube 20 of FIG. 3 is illustrated in FIG. 4 by the symbolic representation FT. The production of a flash of light by the tube FT when the photoelectric cell R is illuminated may be explained by referring to FIG. 4. A source of alternative current is converted to direct current' by a. rectifier bridge 40 which provides the required DC voltage to the circuit. When the flash tube FT is expected to be used in the tunnel, it should be ready to discharge a flash of light as soon as a positive variation of illumination reaches the photoelectric cell R,,. It is therefore a variation from dark to light which actuates to the flash tube FT.

When it is dark, C is charged through R C is charged through R, and R and the silicon controlled rectifier SCR is not conductive. The unijunction transistor T is at rest; C is charged through R; and R C, is charged through R R R and The flash tube FT which may be the type FT 151 sold by Canadian General Electric has a voltage of 500 volts at its terminals. I

When there is a constant amount of light falling upon the photoelectric cell, the same thing exists as stated in the above paragraph, except that the cell R, has a lower resistance and therefore, the capacitor C is charged at a lower voltage then in the dark.

When there is a sudden transition from dark to light, the resistance of the photoelectric cell drops sharply. This drop is differenciated by the capacitor C: which transmits a negative pulse to the base of the unijunction transistor T This reduces the peak voltage in the unijunction transistor T which initiates a relaxation and consequently the capacity C, is discharged through the resistor R It therefore appears at the terminals of the resistor R, an instantaneous peak voltage which is applied to the grid of the silicon controlled rectifier SCR which establishes the contact during the discharge of the capacitor C through the said rectifier SCR and the primary of the trigger coil TC. The silicon controlled rectifier SCR now becomes non-conductive. The pulse transmitted to the primary of the coil TC is raised to a very high voltage into the secondary winding. This triggers the flash tube FT which becomes conductive and enables the capacitor C to discharge into the flash tube FT.

The Zener diode Z, is located to prevent all the excess voltages in the circuit and the capacitor C absorbs the drop of voltage at the terminals of the circuit in order to prevent the influence of other flash tubes.

The synchronization of the illumination of one image with the passage of a window train in front of the said image may be obtained with the combination described above for the benefit of a passenger positioned in front of the said window. However, this arrangement is particularly useful when a plurality of images such as 16a, 16b, 16c, etc. are disposed side by side and are illuminated consecutively in synchronization with the passage of the window. If each image represents a stage of a movement to be reproduced by a figure in the image, a stroboscopic effect will be obtained, that is,

the observer or passenger will have the impression to see only one image in which a figure will be moving or a scenery will be animated.

A series of images will be mounted in the tunnel, preferably in the portion where the train has a uniform speed V. If L is the distance between two consecutive images, L VT, wherein T, is the duration between the passage of two successive images in front of the same point of the train. If the electronic flash tube illuminates the image for a period shorter'than T the image will become visible to the observer only when the window through which he looks will pass before the image. The persistence of the retina will give the impression of seeing a continuously lighted image. In order to minimize the sliding effect of the image, the duration of the flash must be as short as possible. This is particularlyuseful due to the proximity of the image with the observer.

Each image has its own triggering and illuminating system. This facilitates the synchronization and pro.- vides more reliable results. For instance, if one cell or one flash fails to perform, all the other images may be seen.

The time delay circuit will be set so that the flash tube will not be able to be re-energized within a predetermined period which would be slightly less than the time required for the passage of two consecutive windows. This will prevent any stray light to effect the cell and consequently to produce undesired flashing lights. The present system is particularly conceived for illuminating images on the wall of the tunnel closer to the train. If the projection of the image happens when two trains cross, no interference should happen in the normal procedure because the cell, as explained above, is oriented in such a way that the train on the other tracks would not excite the cell. Furthermore, the train adjacent the wall 14 becomes an obstruction for the undesired light coming from the train rolling on the other track. I The maintenance of the system is practically negligible due to its simplicity. The flash tube may be located in a transparent box and the image covered by a clear plastic plate may be easily cleaned. The cell located inside a rather small tubular member is well protected against the dust and corrosion.

The power of the flash tube may be small due to its proximity to the image.

In order to obtain a good quality of the stroboscopic effect, the frequency of the image is preferred to be about 24 frames per second. This may be obtained by changing the speed of the train or the size of the images. During the normal operation of the train, its speed cannot be changed, but the projection may be limited to the period the train has reached its maximum speed. It is usually preferred to display images which have a size nearly as large as the size of the window. However, the size of the images may be reduced in order to have more images per second as long as the sight of adjacent images does not hinder the desired effect. Since the observer will see the image always from the same angle and in the same direction, it is possible to observe the images at a reduced frequency and maintain a good quality of the stroboscopic effect by providing consecutive steps of the animation which are not too distinct from one another. However, for

publicity purposes, a strict adherence to the optimum quality of the stroboscopic effect is not necessary and the designer of the image can do much to provide special and pleasant effects.

We claim:

1. A display system for conveying a message to a passenger located by a window inside a moving subway illumination through said window falls upon it, whereby each image is illuminated only when the passenger moves in front thereof, the said display includes a time delay circuit having a unijunction transistor responsive to the photoelectric cell, a silicon controlled rectifier responsive to said transistor and a trigger coil responsive to the said rectifier, whereby a drop of resistance in the photoelectric cell produces a drop of the peak voltage in the unijunction transistor, 21 conduction through the silicon controlled rectifier and a high voltage in the trigger coil which initiates a discharge through the flash tube. 

1. A display system for conveying a message to a passenger located by a window inside a moving subway train having internal illumination, the said system comprising: a series of images disposed on a wall of a subway tunnel at the level of said window; an electronic flash tube mounted adjacent each image for illuminating said image; a photoelectric cell for each tube and means for mounting said cell so that it is energized only as the illumination through said window falls upon it, whereby each image is illuminated only when the passenger moves in front thereof, the said display includes a time delay circuit having a unijunction transistor responsive to the photoelectric cell, a silicon controlled rectifier responsive to said transistor and a trigger coil responsive to the said rectifier, whereby a drop of resistance in the photoelectric cell produces a drop of the peak voltage in the unijunction transistor, a conduction through the silicon controlled rectifier and a high voltage in the trigger coil which initiates a discharge through the flash tube. 